only if at least 15 roentgens could be saved by suck action; and at 50 roentgens or higher evacuetion would be indicated without regard to¥the possible savings in radiation dose. In making a rough estimate cf radiaticn doses, one may calculate nr. theoretical maxime: infinity gamma dose and then crditrarily civide ty some number such as "2" for en estinate of dese actually received, Whereas this may be satisfactory as a first approximation, a more accurate estimate should be attempted, especially when dealing with doses that might constitute a health hezard,. Owing to the necessity cf making early meesurerents and decisicns, it js to be expected that dose-:ate readings, teken with survey ::sters, will be the available evidence at the times of concern, Table I> suz- marizes the parameters considered in estimating an effective biological cose based on dose=-reate readings. Vieaaeerzt ‘